Projection display system and attaching device

ABSTRACT

A projection display system includes: an image projection device projecting an image on a projection surface; an optical detecting device; and an attaching device, wherein the optical detecting device includes an irradiating section emitting an irradiation light toward a detection region which is set along the projection surface, a light receiving section receiving a reflected light generated as a result of the irradiation light being reflected from the object, and a detecting section detecting position information of the object based on the result of the light received by the light receiving section, and the attaching device includes a first attaching section attached to a support supporting the attaching device, a second attaching section attached to the image projection device, and a third attaching section attached to the optical detecting device.

BACKGROUND

1. Technical Field

The present invention relates to attaching devices and projectiondisplay devices etc.

2. Related Art

In recent years, in electronic equipment such as a cellular telephone, apersonal computer, a car navigation device, a ticket-vending machine,and a bank terminal, a display device having a position detectingfunction, the display device provided with a display section having afront face on which a touch panel is placed, has been used. This displaydevice allows the user to point at an icon or the like in a displayimage or input information while referring to an image displayed on thedisplay section. As a position detecting method using such a touchpanel, a method using a resistive touch panel or a capacitive touchpanel, for example, has been known.

On the other hand, the display area of a projection display device usingan image projection device (a projector) is wider than that of thedisplay device of the cellular telephone or the personal computer.Therefore, it is difficult to realize position detection by using theabove-described resistive touch panel or capacitive touch panel in theprojection display device.

Moreover, as a method for realizing position detection in the projectiondisplay device, there may be a method by which a position detectingdevice which can optically detect the position of an object is builtinto a housing of the image projection device. However, with thismethod, there is a possibility that the housing of the image projectiondevice increases in size, resulting in an increase in the cost of parts,for example.

Furthermore, as an existing technique related to a position detectingdevice for a projection display device, the techniques disclosed inJP-A-11-345085 and JP-A-2001-142643, for example, have been known.However, such a position detecting device has problems such as anundesirably large system.

SUMMARY

An advantage of some aspects of the invention is to provide an attachingdevice and a projection display device etc. which can realize objectposition detection etc. in an image projection device.

An aspect of the invention is directed to an attaching device of animage projection device, the attaching device including a firstattaching section for attaching the attaching device to an attachmentobject to which a device is to be attached, a second attaching sectionfor attaching the image projection device projecting an image on aprojection surface, and a third attaching section for attaching anoptical detecting device detecting an object in a detection region whichis set along the projection surface.

According to the aspect of the invention, the attaching device has thefirst, second, and third attaching sections. In addition, it is possibleto attach the attaching device to the attachment object to which adevice is to be attached, such as a ceiling or a wall, by the firstattaching section and attach the image projection device to theattaching device by the second attaching section. Furthermore, accordingto the aspect of the invention, it is possible to attach the opticaldetecting device to the attaching device by the third attaching sectionand detect, by using the optical detecting device, the object in thedetection region which is set along the projection surface. This makesit possible to realize object position detection etc. in the imageprojection device. Moreover, according to the aspect of the invention,it is possible to attach the image projection device and the opticaldetecting device integrally to the attachment object to which a deviceis to be attached, such as a ceiling or a wall, by the attaching device.Therefore, it is possible to fix the positional relationship between theimage projection device and the optical detecting device. This makes iteasy to ensure the detection accuracy etc. of the optical detectingdevice.

Moreover, according to the aspect of the invention, the image projectiondevice may have a heat dissipation section for dissipating heat to theoutside, and the optical detecting device may be attached, by the thirdattaching section, to a region in which the heat dissipation section isnot placed.

By doing so, it is possible to prevent a reduction in the detectionaccuracy etc. of the optical detecting device due to heated air etc.from the heat dissipation section.

Furthermore, according to the aspect of the invention, the attachingdevice may include an incident light regulating section regulating theentrance of a light in an incident direction intersecting the plane ofthe detection region into the optical detecting device.

By doing so, it is possible to prevent a reduction in the detectionaccuracy etc. of the optical detecting device as a result of the lightin the incident direction intersecting the plane of the detection region(the plane along the projection surface) entering the optical detectingdevice.

In addition, according to the aspect of the invention, the incidentlight regulating section may regulate the entrance of a reflected lightinto the optical detecting device, the reflected light generated as aresult of a projection light from the image projection device beingreflected from the projection surface or the reflected light generatedas a result of an irradiation light from the optical detecting devicebeing reflected from the projection surface or the image projectiondevice.

By doing so, it is possible to prevent a reduction in the detectionaccuracy etc. of the optical detecting device due to the entrance of thereflected light into the optical detecting device, the reflected lightgenerated as a result of the projection light from the image projectiondevice being reflected from the projection surface or the reflectedlight generated as a result of the irradiation light from the opticaldetecting device being reflected from the projection surface or theimage projection device.

Moreover, according to the aspect of the invention, the incident lightregulating section may be an incident light slit having a slit surfacein a direction along the plane of the detection region.

By providing such an incident light slit, it is possible to regulateeffectively the entrance of the light in the incident directionintersecting the plane of the detection region into the opticaldetecting device.

Furthermore, according to the aspect of the invention, an antireflectivelayer or a depressed section may be provided on the slit surface.

By providing an antireflective layer or a depressed section on the slitsurface, it is possible to regulate the entrance of the light reflectedfrom the slit surface into the optical detecting device and therebyprevent a reduction in the detection accuracy etc. of the opticaldetecting device more effectively.

In addition, according to the aspect of the invention, the incidentlight slit may have a first slit surface and a second slit surface whichare provided so as to sandwich the optical detecting device as the slitsurface.

By doing so, it is possible to regulate the entrance of the light in theincident direction intersecting the plane of the detection region intothe optical detecting device on both the first slit surface and thesecond slit surface.

Moreover, according to the aspect of the invention, the opticaldetecting device may have an irradiation light slit regulating anirradiation light for detecting the object, the irradiation lightemitted from the optical detecting device, such that the irradiationlight travels in a direction along the plane of the detection region,and, when the height from the third attaching section to an end of theincident light slit is HS1 and the height from the third attachingsection to an end of the irradiation light slit is HS2, HS1>HS2 mayhold.

By doing so, the direction of the irradiation light from the opticaldetecting device is regulated by the irradiation light slit such thatthe irradiation light travels in a direction along the plane of thedetection region. Moreover, the irradiation light whose irradiationdirection is displaced is regulated due to the presence of the incidentlight slit, such that the irradiation light does not travel toward theimage projection device or the projection surface. This makes itpossible to regulate the entrance of the reflected light reflected fromthe image projection device or the projection surface into the opticaldetecting device.

Furthermore, according to the aspect of the invention, the attachingdevice may further include the optical detecting device attached by thethird attaching section, and the optical detecting device may include anirradiating section emitting an irradiation light toward the detectionregion, the irradiation light for detecting the object, a lightreceiving section receiving a reflected light generated as a result ofthe irradiation light being reflected from the object, and a detectingsection detecting position information of the object based on the resultof the light received by the light receiving section.

By doing so, the irradiating section emits the irradiation light, thelight receiving section receives the reflected light generated as aresult of the irradiation light being reflected from the object, and theposition information of the object can be detected based on the resultof the received light. Therefore, it is possible to realize detection ofthe object in the image projection device with a relatively smallconfiguration.

In addition, according to the aspect of the invention, the irradiatingsection may emit irradiation lights with different intensities inaccordance with the position in the detection region.

By doing so, the intensity of the reflected light reflected from theobject changes according to the position of the object in the detectionregion, whereby it is possible to detect the position, the direction,etc. in which the object is located.

Moreover, according to the aspect of the invention, the irradiatingsection may include a light source section emitting a source light, alight guide which is curved and guides the source light from the lightsource section along a curved light guiding path, and an irradiationdirection setting section receiving the source light exiting from anouter circumferential side of the light guide and setting an irradiationdirection of the irradiation light such that the irradiation lighttravels from an inner circumferential side to the outer circumferentialside of the curved light guide.

According to the aspect of the invention, the source light from thelight source section is guided along the curved light guiding path ofthe light guide. In addition, the source light exiting from the outercircumferential side of the light guide is made to exit as anirradiation light traveling from the inner circumferential side to theouter circumferential side of the light guide. When the exiting light isreflected from the object, the reflected light is received by the lightreceiving section, and the direction etc. in which the object is locatedis detected based on the result of the received light. Therefore, sincethe irradiation light is made to exit radially from the innercircumferential side to the outer circumferential side of the lightguide and the object is detected based on the reflected light generatedas a result of the irradiation light being reflected from the object, itis possible to sense the object in a wide range.

Moreover, according to the aspect of the invention, the opticaldetecting device may have a first irradiating section and a secondirradiating section as the irradiating section, the first irradiatingsection may radially emit first irradiation lights with differentintensities in accordance with the irradiation direction, the secondirradiating section may radially emit second irradiation lights withdifferent intensities in accordance with the irradiation direction, thelight receiving section may receive a first reflected light generated asa result of the first irradiation light from the first irradiatingsection being reflected from the object and a second reflected lightgenerated as a result of the second irradiation light from the secondirradiating section being reflected from the object, and the detectingsection may detect the position of the object based on the result of thelight received by the light receiving section.

According to the aspect of the invention, the first irradiation lightswith different intensities in accordance with the irradiation directionare radially emitted from the first irradiating section, and the secondirradiation lights with different intensities in accordance with theirradiation direction are radially emitted from the second irradiatingsection. Then, the first reflected light generated as a result of thefirst irradiation light being reflected from the object and the secondreflected light generated as a result of the second irradiation lightbeing reflected from the object are received by the light receivingsection, and the position of the object is detected based on the resultof the received light. Therefore, since the position of the object canbe detected by using the first reflected light generated as a result ofthe radially-emitted first irradiation light being reflected from theobject and the second reflected light generated as a result of theradially-emitted second irradiation light being reflected from theobject, it is possible to detect the position of the object in a widerange.

Furthermore, according to the aspect of the invention, the detectingsection may detect position information of the object in the detectionregion after the image projection device projects an image of a screenfor calibration on the projection surface, and the optical detectingdevice may transmit the detected position information of the object tothe image projection device or an information processor controlling theimage projection device.

By doing so, when, for example, the user performs operation according toan instruction on the screen for calibration while viewing the image ofthe screen for calibration projected on the projection surface, theposition information of an object such as a finger of the user or atouch pen is detected. Then, the detected position information istransmitted to the image projection device or the information processor.Therefore, it is possible to perform calibration processing by using theposition information of the object, the information obtained when theimage of the screen for calibration is projected, and improve thedetection accuracy etc. of the optical detecting device.

In addition, according to the aspect of the invention, the opticaldetecting device may include an interface section, and the opticaldetecting device may transmit information for calibration via theinterface section.

By doing so, the optical detecting device can transmit the informationfor calibration such as a program product for calibration and detectedposition information at the time of calibration to the image projectiondevice, the information processor controlling the image projectiondevice, or the like, via the interface section. This makes it possibleto perform calibration processing efficiently.

Moreover, according to the aspect of the invention, the opticaldetecting device may receive a power supply from the image projectiondevice via the interface section.

By doing so, the optical detecting device can operate by the powersupply from the image projection device by making effective use of theinterface section performing interface processing between the opticaldetecting device and the image projection device.

Another aspect of the invention relates to a projection display deviceincluding the attaching device described above and the image projectiondevice attached to the attaching device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 shows a configuration example of an attaching device etc. of animage projection device of an embodiment.

FIG. 2 is an explanatory diagram of a technique of providing an opticaldetecting device in a region in which a heat dissipation section of theimage projection device is not placed.

FIGS. 3A to 3C are explanatory diagrams of a technique of providing theoptical detecting device in a region in which the heat dissipationsection of the image projection device is not placed.

FIGS. 4A and 4B are explanatory diagrams explaining a problem ofdisplacement of a detected position caused by a reflected light.

FIG. 5 is an explanatory diagram of a technique of providing an incidentlight regulating section.

FIGS. 6A to 6C show specific examples of the incident light regulatingsection and an irradiation direction regulating section.

FIG. 7 shows a modified example of the attaching device of thisembodiment.

FIG. 8 is an explanatory diagram of a detection technique using anoptical detecting device.

FIGS. 9A and 9B are explanatory diagrams of the detection techniqueusing the optical detecting device.

FIGS. 10A and 10B are explanatory diagrams of the detection techniqueusing the optical detecting device.

FIG. 11 shows a configuration example of the optical detecting device.

FIGS. 12A and 12B are examples of a signal waveform for explaining thedetection technique using the optical detecting device.

FIG. 13 shows a modified example of the optical detecting device.

FIGS. 14A and 14B are explanatory diagrams of the irradiation directionregulating section.

FIG. 15 is a side view showing a detailed structural example of theattaching device.

FIGS. 16A and 16B are front views showing a detailed structural exampleof the attaching device.

FIG. 17 is an explanatory diagram of a technique of performingcalibration etc. by providing an interface section.

FIG. 18 is a flowchart for explaining a specific example of calibrationprocessing.

FIGS. 19A to 19C are explanatory diagrams of a calibration technique.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a preferred embodiment of the invention will be describedin detail. It should be understood that the embodiment described belowis not meant to limit unduly the scope of the invention claimed in theappended claims in any way, and all the configurations described in theembodiment are not always necessary for means for solving the problems.

1. Configuration of Attaching Device

In FIG. 1, a configuration example of a projection display deviceincluding an attaching device of this embodiment and an image projectiondevice 10 attached to the attaching device is shown. FIG. 1 shows anexample in which the attaching device (in a more limited sense,ceiling-hung fittings) of this embodiment is used as an attaching deviceof an image projection device 10 called a liquid crystal projector or adigital micromirror device. In addition, the attaching device and theimage projection device 10 attached to the attaching device form aprojection display device. Incidentally, in FIG. 1, intersecting axes(axes orthogonal to each other) are assumed to be an X axis, a Y axis,and a Z axis (in a broad sense, first, second, and third coordinateaxes). Specifically, a plane parallel to a projection surface 22 (ascreen) onto which the image projection device 10 projects an image isan X-Y plane defined by the X axis and the Y axis, and a directionintersecting (orthogonal to) the X-Y plane is a direction of the Z axis.

The image projection device 10 enlarges an image display light andprojects the image display light from a projecting section 12 having anoptical system such as a projection lens toward the projection surface22 such as a screen or a wall. Specifically, the image projection device10 generates a display light of a color image and emits the displaylight toward the projection surface 22 via the projecting section 12. Asa result, the color image is displayed on the projection surface 22.

The attaching device (the ceiling-hung fittings) of this embodiment,shown in FIG. 1, has first, second, and third attaching sections 31, 32,and 33.

The first attaching section 31 (a first bracket, a first fixing member)is provided for attaching the attaching device to a ceiling 400 (asupport, in a broad sense, an attachment object to which a device is tobe attached), and is a member (fittings) for securing the attachingdevice to the ceiling 400, for example. The attaching section 31 isformed of, for example, fittings serving as a base, attaching fittings(screws, nuts) for securing the attaching device to the ceiling 400, andthe like.

The second attaching section 32 (a second bracket, a second fixingmember) is provided for attaching the image projection device 10 (in abroad sense, an image generating apparatus, electronic equipment) whichprojects an image onto the projection surface 22, and is, for example, amember (fittings) for securing the image projection device 10 to theattaching device. The attaching section 32 is formed of, for example,fittings serving as a base, attaching fittings for securing the imageprojection device 10 to the attaching device, and the like.

The third attaching section 33 (a third bracket, a third fixing member)is provided for attaching an optical detecting device 40, and is, forexample, a member (fittings) for securing the optical detecting device40 to the attaching device. The attaching section 33 is formed of, forexample, fittings serving as a base, attaching fittings for securing theoptical detecting device 40 to the attaching device, and the like.

Incidentally, the attaching sections 31, 32, and 33 may be integrallyformed. For example, the base fittings of the attaching section 32 andthe base fittings of the attaching section 33 may be integrated togetherinto a single member, or may be coupled together by a joining section (ajoint). Moreover, the optical detecting device 40 may be detachablyattached to the attaching device, or may be secured to the attachingdevice in an undetachable way.

The optical detecting device 40 is a device for optically detecting anobject OB in a detection region RDET. For example, as shown in FIG. 1,the detection region RDET is a region which is set along the projectionsurface 22 (a display region). Specifically, the detection region RDETis a region which is set along the X-Y plane on the Z direction's side(the user's side) of the projection surface 22 (the screen).

The optical detecting device 40 optically detects the object OB such asa finger of the user or a touch pen in the detection region RDET whichis set on the front side (the Z direction's side) of the projectionsurface 22. To detect the object OB, the optical detecting device 40includes an irradiating section, a light receiving section, and adetecting section, which are not shown in the drawing. The irradiatingsection emits an irradiation light for detecting the object OB towardthe detection region RDET. For example, the irradiating section emitsthe irradiation lights with different intensities (intensities ofillumination) in accordance with the position in the detection regionRDET. The light receiving section receives the reflected light generatedas a result of the irradiation light being reflected from the object OBsuch as the finger or the touch pen. The light receiving section RU isimplemented, for example, in the form of a light receiving element suchas a photodiode or a phototransistor. The detecting section detects theposition information of the object OB based on the result of the lightreceived by the light receiving section. The position information of theobject OB is, for example, the X and Y coordinates or the Z coordinateof the object OB. Instead, the position information of the object OB maybe a direction in which the object OB is located.

As described above, in this embodiment, the attaching section 33 forattaching the optical detecting device 40 is provided in the attachingdevice for attaching the image projection device 10 to the attachmentobject to which a device is to be attached, such as the ceiling 400. Bydoing so, it is possible to attach the optical detecting device 40 as anoptional unit and thereby expand the range of user choices of options.Moreover, by attaching the optical detecting device 40, it is possibleto provide an interactive user interface for the contents projected bythe image projection device 10. For example, the user is allowed toindicate a displayed object in an image by using a finger or a touch penwhile projecting the image of the presentation material on theprojection surface 22 by the image projection device 10. This makes itpossible to realize an unprecedented user interface.

Moreover, for example, as a first technique which is a comparativeexample of this embodiment, there may be a technique of incorporatingthe optical detecting device 40 into a housing (a case) of the imageprojection device 10 (the projector).

However, with this first technique, the housing of the image projectiondevice 10 increases in size, resulting in an increase in the cost, forexample. Moreover, it is difficult to handle both the user who requiresthe optical detecting device 40 and the user who does not require theoptical detecting device 40.

On the other hand, according to this embodiment, as shown in FIG. 1,since the optical detecting device 40 is provided outside the imageprojection device 10, it is possible to prevent the above-mentionedproblem of an increase in size of the housing of the image projectiondevice 10. Moreover, it is possible to handle the user who requires theoptical detecting device 40 by attaching the optical detecting device 40to the attaching device, and it is possible to handle the user who doesnot require the optical detecting device 40 by removing the opticaldetecting device 40 from the attaching device or not attaching theoptical detecting device 40 to the attaching device.

Furthermore, as a second technique which is a comparative example ofthis embodiment, there may be a technique of allowing the user to attachthe optical detecting device 40 in an arbitrary location.

However, with this second technique, as will be described later, thedetection accuracy cannot be ensured in some locations in which theoptical detecting device 40 is placed. In addition, it is troublesomefor the user to attach the optical detecting device 40 to the ceiling400 or the like in an extra operation.

On the other hand, according to this embodiment, by using the attachingdevice as shown in FIG. 1, the positional relationship between the imageprojection device 10 and the optical detecting device 40 is fixed.Therefore, as will be described later, it is possible to place and fixthe optical detecting device 40 in a region in which a heat dissipationsection of the image projection device 10 is not placed or provide anincident light regulating section regulating the incident light whichreduces the detection accuracy. This makes it easy to ensure thedetection accuracy etc. of the optical detecting device 40. In addition,when the image projection device 10 is attached to the ceiling 400 bythe attaching device, it is possible to attach the optical detectingdevice 40 together with the image projection device 10. This makes itpossible to prevent an addition of a troublesome operation which isperformed by the user and provide the user with improved convenience.

2. Displacement of Detected Position Due to Heat Dissipation

As shown in FIG. 2, the image projection device 10 is provided with aheat dissipation section 14 for dissipating heat built up in thehousing. Specifically, a fan and an exhaust port for exhausting the airinside the housing are provided as the heat dissipation section 14.

However, if the optical detecting device 40 is placed in a locationwhich is exposed to the heated air from the heat dissipation section 14such as a fan, there is a possibility that displacement of the detectedposition of the object OB is caused due to, for example, the temperaturedependence of the characteristics of an element (a light receivingelement, a light emitting element, a transistor, and the like) of theoptical detecting device 40. For example, as in the above-describedsecond technique, in the technique in which the user places the opticaldetecting device 40 in an arbitrary location, the displacement of thedetected position varies depending on the position in which the opticaldetecting device 40 is placed, and it is difficult to make an adjustmentthereto. Moreover, since the state of dissipation of heat from the heatdissipation section 14 of the image projection device 10 changes withtime, the displacement of the detected position varies, for example, ina period in which heat is often dissipated and a period in which heat isnot dissipated frequently.

Therefore, in the attaching device of this embodiment, as shown in FIG.2, when the image projection device 10 has the heat dissipation section14 for dissipating heat to the outside, the optical detecting device 40is attached, by the attaching section 33, in a region in which the heatdissipation section 14 is not placed. For example, the attaching section33 is provided in a region in which the heat dissipation section 14 isnot placed, and the optical detecting device 40 is attached by thisattaching section 33.

Specifically, in FIG. 2, the heat dissipation section 14 is provided ina back side of the image projection device 10 (a side thereof oppositeto the projection surface 22). As a result, the optical detecting device40 is attached to a front side of the image projection device 10 (a sidethereof facing the projection surface 22) by the attaching section 33 ofthe attaching device. That is, the attaching section 33 is provided in alocation in which the optical detecting device 40 is less exposed to theheated air from the fan which is the heat dissipation section 14.

As described above, by attaching the optical detecting device 40 in aregion in which the heat dissipation section 14 is not placed (a regionwhich is not exposed to the heat from the heat dissipation section) bythe attaching section 33, it is possible to solve the problem ofdisplacement of the detected position caused by the heat from the heatdissipation section 14.

In particular, this embodiment focuses on the positional relationshipbetween the image projection device and the optical detecting device 40,the positional relationship which is fixed via the attaching device. Theuse of such a fixed positional relationship makes it possible to placethe optical detecting device 40 in a region in which the opticaldetecting device 40 is not exposed to the heat from the heat dissipationsection 14 and prevent the problem of displacement of position detectioneffectively.

Incidentally, in this embodiment, the optical detecting device 40 (theattaching section 33) is placed in a region in which the heatdissipation section 14 is not placed. Some examples of a region in whichthe heat dissipation section 14 is not placed are shown in FIGS. 3A to3C.

For example, in FIG. 3A, the heat dissipation section 14 is providedbehind the image projection device 10 (the housing). In this case, theoptical detecting device 40 is attached in a position in which theoptical detecting device 40 faces the left side, the right side, or thefront face, for example, of the image projection device 10.

Moreover, in FIG. 3B, the heat dissipation section 14 is provided on thefront face of the image projection device 10. In this case, the opticaldetecting device 40 is attached to a position in which the opticaldetecting device 40 faces the left side, the right side, or the backface of the image projection device 10.

Furthermore, in FIG. 3C, the heat dissipation section 14 is provided onthe left side of the image projection device 10. In this case, theoptical detecting device 40 is attached to a position in which theoptical detecting device 40 faces the right side, the front face, or theback face of the image projection device 10.

As described above, in this embodiment, when the heat dissipationsection 14 is provided on any one of the front face, the back face, theleft side, and the right side of the image projection device 10, theoptical detecting device 40 is attached to a position in which theoptical detecting device 40 faces a face or side other than the aboveone face or side. By doing so, attachment of the optical detectingdevice 40 in a region in which the heat dissipation section 14 is notplaced is realized.

3. Displacement of Detected Position Due to Reflected Light

In FIG. 4A, a short focus image projection device 10, for example, isattached to the ceiling 400 by the attaching device. The projectionlight projected from the image projection device 10 is reflected fromthe projection surface 22 such as a screen, and infrared light containedin the reflected light enters the optical detecting device 40. Asdescribed above, when the light other than the reflected light from theobject such as a finger of the user or a touch pen enters the lightreceiving element of the optical detecting device 40, displacement ofthe detected position may occur. In particular, as shown in FIG. 1,since the detection region RDET of the optical detecting device 40 isset in a front region just near the projection surface 22, there is ahigh possibility that the light reflected from the projection surface 22enters the optical detecting device 40.

Moreover, in FIG. 4B, the optical detecting device 40 is attachedbetween the image projection device 10 and the wall on which theprojection surface 22 is located. The irradiation light emitted from theoptical detecting device 40 is reflected by the housing of the imageprojection device 10, and the reflected light enters the opticaldetecting device 40. Moreover, the irradiation light from the opticaldetecting device 40 is reflected from the projection surface (the wall),and the reflected light enters the optical detecting device 40. Also inthis case, there is a possibility that the level of the default lightentering the light receiving element of the optical detecting device 40changes and displacement of the detected position occurs.

It is for this reason that, in this embodiment, an incident lightregulating section which regulates the entrance of the light in theincident direction intersecting the plane of the detection region RDET(the X-Y plane) into the optical detecting device 40 is provided.Specifically, as shown in FIG. 5, an incident light slit SLB having aslit surface in a direction (a direction parallel to the projectionsurface) along the plane of the detection region RDET (the X-Y plane) isprovided. For example, the incident light slit SLB of FIG. 5 has a firstslit surface SLB1 and a second slit surface SLB2 which are provided soas to sandwich the optical detecting device 40.

Such an incident light regulating section implemented in the form of theincident light slit SLB or the like regulates (restricts) the entranceof a reflected light into the optical detecting device 40, the reflectedlight generated as a result of the projection light from the imageprojection device 10 being reflected from the projection surface 22 asshown in FIG. 4A, or regulates (restricts) the entrance of a reflectedlight into the optical detecting device 40, the reflected lightgenerated as a result of the irradiation light from the opticaldetecting device 40 being reflected from the projection surface 22 orthe image projection device 10 as shown in FIG. 4B. That is, theincident light regulating section is formed of a member which is shapedand placed so as to regulate the entrance of the reflected lights shownin FIGS. 4A and 4B into the optical detecting device 40.

By providing such an incident light regulating section such as theincident light slit SLB or the like, it is possible to preventdisplacement of the detected position caused by the entrance of thereflected lights as shown in FIGS. 4A and 4B and ensure the detectionaccuracy of the optical detecting device 40.

In particular, since the image projection device 10 and the opticaldetecting device 40 are attached as an integrated member by theattaching device of this embodiment, the positional relationship betweenthese devices is fixed. Therefore, such a fixed positional relationshipmakes it possible to set easily the shape and the placement of theincident light regulating section which prevents the reflected lightfrom the image projection device 10 or the like from entering theoptical detecting device 40. That is, as described earlier, in thetechnique of the comparative example in which the user sets the opticaldetecting device 40 in an arbitrary location, it is necessary to providean incident light regulating section in such a way as to deal with casesin which the optical detecting device 40 is set in various locations.This makes it difficult to set the shape and the placement of theincident light regulating section. On the other hand, with the attachingdevice of this embodiment, since the positional relationship between theimage projection device 10 and the optical detecting device 40 is fixed,it is possible to deal with cases in which the optical detecting device40 is set in various locations just by providing the incident light slitSLB which is shaped and placed as shown in FIG. 5, for example.

Furthermore, in this embodiment, as shown in FIG. 6A, it is preferableto provide antireflective layers (antireflective films) RPL1 and RPL2 onthe slit surfaces SLB1 and SLB2. For example, the antireflective layersRPL1 and RPL2 are formed by applying nonreflective coating to the slitsurfaces SLB1 and SLB2. By doing so, it is possible to regulate theentrance of the light reflected from the slit surfaces SLB1 and SLB2into the light receiving element of the optical detecting device 40 andprevent a reduction in the detection accuracy etc. of the opticaldetecting device 40.

Incidentally, in place of the antireflective layers RPL1 and RPL2, adepressed section may be provided on the slit surfaces SLB1 and SLB2 asshown in FIG. 6B. That is, in FIG. 5, the slit surfaces SLB1 and SLB2are flat; in FIG. 6B, the slit surfaces SLB1 and SLB2 are not flat, butdepressed. By providing such a depressed section, it is possible toprevent surface reflection on the slit surfaces SLB1 and SLB2. Thismakes it possible to regulate the entrance of unnecessary reflectedlight into the light receiving element of the optical detecting device40 and prevent a reduction in the detection accuracy etc. of the opticaldetecting device 40.

Moreover, in FIG. 6C, as will be described later, the optical detectingdevice 40 has an irradiation light slit SL (an irradiation directionregulating section). The irradiation light slit SL regulates theirradiation light for object detection, the irradiation light emittedfrom the optical detecting device 40, such that the irradiation lighttravels in a direction (a direction parallel to the projection surface)along the plane of the detection region RDET (the X-Y plane) of FIG. 1,and has first and second slit surfaces SFL1 and SFL2. By providing suchan irradiation light slit SL, it is possible to regulate the irradiationdirection of the irradiation light emitted from the optical detectingdevice 40 such that the irradiation light travels in a direction alongthe plane of the detection region RDET. Therefore, it is possible toprevent the irradiation light toward the detection region RDET fromspreading in the Z direction of FIG. 1 and prevent the body of the userfrom being erroneously detected as an object such as a finger or a touchpen when the body of the user approaches the screen 20.

In FIG. 6C, assume that the height from the attaching section 33 to theend of the incident light slit SLB is HS1 and the height from theattaching section 33 to the end of the irradiation light slit SL is HS2.Then, in FIG. 6C, HS1>HS2 holds. That is, the incident light slit SLB ishigher than the irradiation light slit SL.

By doing so, the direction of the irradiation light from the opticaldetecting device 40 is regulated by the irradiation light slit SL suchthat the irradiation light travels in a direction along the plane of thedetection region RDET. Moreover, due to the presence of the incidentlight slit SLB, the irradiation light whose irradiation direction isdisplaced in the Z direction is also regulated such that the irradiationlight does not travel toward the image projection device 10 or theprojection surface 22 as shown in FIG. 4B, and it is possible toregulate the entrance of the reflected light reflected from the imageprojection device 10 or the projection surface 22 into the opticaldetecting device 40. Therefore, it is possible to prevent a reduction inthe detection accuracy etc. caused by the entrance of the reflectedlight.

Incidentally, the descriptions heretofore mainly deal with a case inwhich the optical detecting device 40 is attached between the imageprojection device 10 and the projection surface 22 by the attachingdevice of this embodiment. However, this embodiment is not limitedthereto. For example, as shown in a modified example of FIG. 7, theoptical detecting device 40 may be attached by providing the attachingsection 33 on a back side of the image projection device 10 (a sidethereof opposite to the projection surface). For example, it ispreferable to provide the optical detecting device 40 in a positionshown in FIG. 7 in the short focus image projection device 10 which canproject a large image on the projection surface 22 even if the distanceto the projection surface 22 is a short distance such as a distance of 8to 20 cm.

In addition, in this case, it is necessary simply to provide aplate-like incident light regulating section SLC shown in FIG. 7, forexample, between the image projection device 10 and the opticaldetecting device 40. By providing such an incident light regulatingsection SLC, it is possible to prevent the projection light from theimage projection device 10 from being reflected from the projectionsurface 22 or the like and entering the optical detecting device 40. Itis also possible to prevent an increase in the level of the defaultlight as a result of the irradiation light from the optical detectingdevice 40 being reflected from the image projection device 10 or theprojection surface 22 and entering the optical detecting device 40. Thismakes it possible to maintain the accuracy of position detection of theoptical detecting device 40.

4. Configuration of Optical Detecting Device

Next, a configuration example of the optical detecting device will bedescribed. The optical detecting device of FIG. 8 includes anirradiating section EU, a light receiving section RU, and a detectingsection 50. Moreover, the optical detecting device can include a controlsection 60.

The irradiating section EU emits an irradiation light (a detectionlight) for detecting an object. Specifically, the irradiating section EUradially emits irradiation lights with different intensities(intensities of illumination) in accordance with the irradiationdirection. As a result, in the detection region RDET (see FIG. 1), anirradiation light intensity distribution in which the intensity of theirradiation light differs in accordance with the irradiation directionis formed.

The light receiving section RU receives a reflected light generated as aresult of the irradiation light from the irradiating section EU beingreflected from the object. The light receiving section RU can beimplemented in the form of a light receiving element such as aphotodiode or a phototransistor. The detecting section 50 is, forexample, electrically connected to the light receiving section RU.

The detecting section 50 detects at least the direction etc. in whichthe object is located based on the result of the light received by thelight receiving section RU. The function of the detecting section can berealized by an integrated circuit device having an analog circuit andthe like, software (a program product) operating on a microcomputer, andthe like. For example, the detecting section converts the detectioncurrent generated as a result of the light receiving element of thelight receiving section having received the reflected light from theobject into a detection voltage, and detects the position, thedirection, etc. in which the object is located based on the detectionvoltage which is the result of the received light.

Specifically, the detecting section 50 detects the distance to theobject (the distance from the position in which the irradiating sectionis placed) based on the result of the light received by the lightreceiving section RU (the received-light signal). The detecting section50 detects the position of the object based on the detected distance andthe detected direction in which the object is located (the direction inwhich the object is present). For example, the detecting section 50detects the X and Y coordinates in the X-Y plane of the detection regionRDET. Incidentally, first and second irradiating sections which are agiven distance away from each other along the X-axis direction may beprovided. In this case, the detecting section 50 detects the directionin which the object is located with respect to the first irradiatingsection as a first direction based on the result of the received light,i.e., a first reflected light generated as a result of a firstirradiation light from the first irradiating section being reflectedfrom the object. Moreover, the detecting section 50 detects thedirection in which the object is located with respect to the secondirradiating section as a second direction based on the result of thereceived light, i.e., a second reflected light generated as a result ofa second irradiation light from the second irradiating section beingreflected from the object. The detecting section 50 only has to detectthe position of the object based on the detected first and seconddirections and the distance between the first and second irradiatingsections.

The control section 60 performs various types of control processing ofthe optical detecting device. Specifically, the control section 60performs light emitting control of a light source section of theirradiating section EU. The control section 60 is electrically connectedto the irradiating section EU and the detecting section 50. The functionof the control section 60 can be realized by an integrated circuitdevice, software operating on the microcomputer, and the like. Forexample, when the irradiating section EU includes first and second lightsource sections, the control section 60 performs control so as to makethe first and second light source sections emit light alternately.Moreover, as described above, when the first and second irradiatingsections are provided, in a first period in which the direction in whichthe object is located with respect to the first irradiating section isobtained, the control section 60 performs control so as to make firstand second light source sections provided in the first irradiatingsection emit light alternately. In addition, in a second period in whichthe direction in which the object is located with respect to the secondirradiating section is obtained, the control section 60 performs controlso as to make third and fourth light source sections provided in thesecond irradiating section emit light alternately.

5. Object Detection Technique

Next, an object detection technique according to this embodiment will bedescribed in detail.

As shown in FIG. 9A, the optical detecting device (the irradiatingsection) of this embodiment includes a light source section LS1, a lightguide LG, and an irradiation direction setting section LE. Moreover, theoptical detecting device includes a reflecting sheet RS. In addition,the irradiation direction setting section LE includes an optical sheetPS and a louver film LF. It is to be understood that variousmodifications are possible by omitting part of these component elementsor adding another component element.

The light source section LS1 emits a source light, and has a lightemitting element such as an LED (light-emitting diode). The light sourcesection LS1 emits a source light of infrared light (near infraredradiation close to a visible radiation region), for example. That is, itis preferable that the source light emitted from the light sourcesection LS1 be a light in a wavelength band which is efficientlyreflected from an object such as a finger of the user or a touch pen, ora light in a wavelength band which is seldom contained in environmentallight, i.e., ambient light. Specifically, the source light emitted fromthe light source section LS1 is infrared light of a wavelength near 850nm, which is a light in a wavelength band with a high degree ofreflection on the surface of a human body, or infrared light near 950nm, which is a light in a wavelength band which is seldom contained inenvironmental light.

The light guide LG (a light guiding member) guides the source lightemitted from the light source section LS1. For example, the light guideLG guides the source light from the light source section LS1 along acurved light guiding path, and has a curved shape. Specifically, in FIG.9A, the light guide LG is shaped like an arc. Incidentally, in FIG. 9A,the light guide LG has an arc shape with a central angle of 180 degrees;however, the light guide LG may have an arc shape with a central angleof less than 180 degrees. The light guide LG is formed of a transparentresin member such as acrylic resin or polycarbonate, or the like. Thesource light from the light source section LS1 enters a light entranceface at one end (in FIG. 9A, a left-side end) of the light guide LG.

At least one of an outer circumferential side (a side identified by B1)and an inner circumferential side (a side identified by B2) of the lightguide LG is processed for adjusting the light exit efficiency of thesource light from the light guide LG. As a processing technique, varioustechniques such as silk printing processing by which reflecting dots areprinted, a molding method for forming projections and depressions by astamper or injection, and a grooving method can be adopted.

The irradiation direction setting section LE (the irradiation light exitsection) implemented by using the prism sheet PS and the louver film LFis provided on the outer circumferential side of the light guide LG, andreceives the source light exiting from the outer circumferential side(the outer circumferential surface) of the light guide LG. Then, theirradiation direction setting section LE makes an irradiation light LTexit, the irradiation light LT whose irradiation direction is set sothat the irradiation light LT travels from the inner circumferentialside (B2) to the outer circumferential side (B1) of the curved(arc-shaped) light guide LG. That is, the irradiation direction settingsection LE sets (regulates) the direction in which the source lighttravels, the source light exiting from the outer circumferential side ofthe light guide LG, at an irradiation direction along the normaldirection (the radial direction), for example, of the light guide LG. Asa result, the irradiation light LT is made to exit radially from theinner circumferential side to the outer circumferential side of thelight guide LG.

The above settings of the irradiation direction of the irradiation lightLT are realized by using the prism sheet PS and the louver film LF ofthe irradiation direction setting section LE. For example, the prismsheet PS makes settings so that the peak of the light exitcharacteristics coincides with the normal direction by, for example,making the direction in which the source light travels, the source lightexiting from the outer circumferential side at a low viewing angle,closer to the normal direction. Moreover, the louver film LF blocks(filters out) the light (the light with a low viewing angle) travellingin a direction other than the normal direction. Incidentally, adiffusing sheet or the like may be provided in the irradiation directionsetting section LE. Furthermore, the reflecting sheet RS is provided onthe inner circumferential side of the light guide LG. By providing thereflecting sheet RS on the inner circumferential side as describedabove, it is possible to improve the light exit efficiency of the sourcelight traveling to the outer circumferential side.

As shown in FIG. 9A, as a result of the light source section LS1emitting a source light toward the light entrance face at one end (B3)of the light guide LG, a first irradiation light intensity distributionLID1 is formed in an object detection region. The first irradiationlight intensity distribution LID1 is an intensity distribution in whichthe intensity of the irradiation light is the highest at the one end(B3) of the light guide LG, decreases with increasing distance from theone end (B3), and is the lowest at the other end (B4) of the light guideLG. That is, in FIG. 9A, the magnitude of a vector of the irradiationlight LT represents the intensity (the intensity of illumination), andthe intensity of the irradiation light LT is the highest at the one end(B3) of the light guide LG; the intensity is the lowest at the other end(B4) thereof. In addition, the intensity of the irradiation light LTdecreases monotonously with increasing distance from the one end to theother end of the light guide LG.

On the other hand, as shown in FIG. 9B, as a result of a second lightsource section LS2 emitting a second source light toward the lightentrance face of the other end (B4) of the light guide LG, a secondirradiation light intensity distribution LID2 is formed in the detectionregion. The second irradiation light intensity distribution LID2 has anintensity distribution which is different from that of the firstirradiation light intensity distribution LID1, and is an intensitydistribution in which the intensity of the irradiation light decreaseswith increasing distance from the other end (B4) to the one end (B3) ofthe light guide LG. That is, in FIG. 9B, the intensity of theirradiation light LT is the highest at the other end of the light guideLG, and the intensity is the lowest at the one end thereof. In addition,the intensity of the irradiation light LT decreases monotonously withincreasing distance from the other end to the one end.

By forming the irradiation light intensity distributions LID1 and LID2described above and receiving the reflected lights from the object, thereflected lights generated as a result of the irradiation lights havingthese intensity distributions being reflected from the object, it ispossible to detect the object with a higher degree of accuracy whileminimizing the influence of the ambient light such as the environmentallight. That is, it is possible to cancel out an infrared componentcontained in the ambient light and minimize a negative influence of theinfrared component on the detection of the object.

For example, E1 of FIG. 10A shows a relationship between the angle ofthe irradiation direction of the irradiation light LT and the intensityof the irradiation light LT at that angle in the irradiation lightintensity distribution LID1 of FIG. 9A. In E1 of FIG. 10A, the intensityis the highest when the irradiation direction is a direction DD1 (aleft-hand direction) of FIG. 10B. On the other hand, the intensity isthe lowest when the irradiation direction is a direction DD3 (aright-hand direction), and, in a direction DD2, the intensity is anintensity intermediate between the highest intensity and the lowestintensity. Specifically, with respect to an angle change from thedirection DD1 to the direction DD3, the intensity of the irradiationlight decreases monotonously, for example, changes linearly.Incidentally, in FIG. 10B, the center position of the arc formed by thelight guide LG coincides with a placement position PE in which theoptical detecting device is placed.

Moreover, E2 of FIG. 10A shows a relationship between the angle of theirradiation direction of the irradiation light LT and the intensity ofthe irradiation light LT at that angle in the irradiation lightintensity distribution LID2 of FIG. 9B. In E2 of FIG. 10A, the intensityis the highest when the irradiation direction is the direction DD3 ofFIG. 10B. On the other hand, the intensity is the lowest when theirradiation direction is the direction DD1, and, in the direction DD2,the intensity is an intensity intermediate between the highest intensityand the lowest intensity. Specifically, with respect to an angle changefrom the direction DD3 to the direction DD1, the intensity of theirradiation light decreases monotonously, for example, changes linearly.Incidentally, in FIG. 10A, there is a linear relationship between theangle of the irradiation direction and the intensity; however, thisembodiment is not limited thereto. For example, there may be ahyperbolic relationship between the angle of the irradiation directionand the intensity.

As shown in FIG. 10B, assume that an object OB is present in a directionDDB with an angle θ. Then, when the irradiation light intensitydistribution LID1 is formed as a result of the light source section LS1emitting light as shown in FIG. 9A (in the case of E1), the intensity inthe position of the object OB which is present in the direction DDB(with an angle θ) is INTa as shown in FIG. 10A. On the other hand, whenthe irradiation light intensity distribution LID2 is formed as a resultof the light source section LS2 emitting light as shown in FIG. 9B (inthe case of E2), the intensity in the position of the object OB which ispresent in the direction DDB is INTb.

Therefore, by obtaining the relationship between the intensities INTaand INTb, it is possible to determine the direction DDB (angle θ) inwhich the object OB is located. Then, by obtaining the distance to theobject OB based on the placement position PE in which the opticaldetecting device is placed by using a technique shown in FIGS. 12A and12B, for example, which will be described later, it is possible todetermine the position of the object OB based on the obtained distanceand the direction DDB. Alternatively, by providing two irradiatingsections EU1 and EU2 as shown in FIG. 13 which will be described later,and obtaining directions DDB1 (θ1) and DDB2 (θ2) of the object OB withrespect to the irradiating sections EU1 and EU2, respectively, it ispossible to determine the position of the object OB based on thedirections DDB1 and DDB2 and the distance DS between the irradiatingsections EU1 and EU2.

In order to obtain the relationship between the intensities INTa andINTb, in this embodiment, the light receiving section RU of FIG. 8receives a reflected light (a first reflected light) reflected from theobject OB when the irradiation light intensity distribution LID1 shownin FIG. 9A is formed. When the detected amount of received reflectedlight at this time is assumed to be Ga, Ga corresponds to the intensityINTa. Moreover, the light receiving section RU receives a reflectedlight (a second reflected light) reflected from the object OB when theirradiation light intensity distribution LID2 shown in FIG. 9B isformed. When the detected amount of received reflected light at thistime is assumed to be Gb, Gb corresponds to the intensity INTb.Therefore, when the relationship between the detected amounts ofreceived lights Ga and Gb is obtained, the relationship between theintensities INTa and INTb is obtained, whereby it is possible to obtainthe direction DDB in which the object OB is located.

For example, let a controlled variable (for example, the amount ofcurrent), a conversion factor, and the amount of emitted light of thelight source section LS1 of FIG. 9A be Ia, k, and Ea, respectively, anda controlled variable (the amount of current), a conversion factor, andthe amount of emitted light of the light source section LS2 of FIG. 9Bbe Ib, k, and Eb, respectively. Then, equations (1) and (2) below hold.Ea=k·Ia  (1)Eb=k·Ib  (2)

Moreover, let an attenuation coefficient of a source light (a firstsource light) from the light source section LS1 be fa, the detectedamount of received reflected light (a first reflected light)corresponding to the source light be Ga, an attenuation coefficient of asource light (a second source light) from the light source section LS2be fb, and the detected amount of received reflected light (a secondreflected light) corresponding to the source light be Gb. Then,equations (3) and (4) below hold.Ga=fa·Ea=fa·k·Ia  (3)Gb=fb·Eb=fb·k·Ib  (4)

Therefore, the ratio between the detected amounts of received lights Gaand Gb is given by equation (5) below.Ga/Gb=(fa/fb)·(Ia/Ib)  (5)

Here, it is possible to determine Ga/Gb based on the result of the lightreceived by the light receiving section RU and determine Ia/Ib based onthe controlled variable of the irradiating section EU by the controlsection 60. In addition, there is a unique relationship between theintensities INTa and INTb of FIG. 10A and the attenuation coefficientsfa and fb. For example, when the attenuation coefficients fa and fb aresmall values and the amount of attenuation is large, the intensitiesINTa and INTb are low. On the other hand, when the attenuationcoefficients fa and fb are large values and the amount of attenuation issmall, the intensities INTa and INTb are high. Therefore, by obtainingthe ratio between the attenuation coefficients fa/fb by equation (5)above, it is possible to obtain the direction, the position, etc. inwhich the object is located.

More specifically, one controlled variable Ia is fixed at Im, and theother controlled variable Ib is controlled such that the ratio betweenthe detected amounts of received lights Ga/Gb becomes 1. For example,control is performed such that the light source sections LS1 and LS2 areturned on alternately in opposite phase as shown in FIG. 12A which willbe described later, the waveforms of the detected amounts of receivedlights are analyzed, and the other controlled variable Ib is controlledsuch that no detected waveform is observed (such that Ga/Gb=1). Then, byobtaining the ratio between the attenuation coefficients fa/fb based onthe other controlled variable Ib=(fa/fb) at this time, the direction,the position, etc. in which the object is located are obtained.

Moreover, control may be performed such that Ga/Gb=1 and the sum of thecontrolled variables Ia and Ib becomes constant as in equations (6) and(7) below.Ga/Gb=1  (6)Im=Ia+Ib  (7)

When equations (6) and (7) above are substituted into equation (5)above, equation (8) holds.

$\begin{matrix}\begin{matrix}{{{Ga}/{Gb}} = {1 = {\left( {{fa}/{fb}} \right) \cdot \left( {{Ia}/{Ib}} \right)}}} \\{= {\left( {{fa}/{fb}} \right) \cdot \left\{ {\left( {{Im} - {Ib}} \right)/{Ib}} \right\}}}\end{matrix} & (8)\end{matrix}$

Based on equation (8) above, Ib is given by equation (9) below.Ib={fa/(fa+fb)}·Im  (9)

Here, when α=fa/(fa+fb), equation (9) above is expressed as equation(10) below, and the ratio between the attenuation coefficients fa/fb isexpressed as equation (11) below by using α.Ib=α·Im  (10)fa/fb=α/(1−α)  (11)

Therefore, when control is performed such that Ga/Gb=1 and the sum of Iaand Ib becomes a fixed value Im, α is obtained by equation (10) abovebased on Ib and Im, and, by substituting α thus obtained into equation(11) above, the ratio between the attenuation coefficients fa/fb can beobtained. This makes it possible to obtain the direction, the position,etc. of the object. In addition, by performing control such that Ga/Gb=1and the sum of Ia and Ib becomes constant, it is possible to cancel outthe influence etc. of the ambient light and improve the detectionaccuracy.

Incidentally, the descriptions heretofore deal with the technique ofdetecting the direction, the position, etc. in which the object islocated by forming the irradiation intensity distribution LID1 of FIG.9A and the irradiation light intensity distribution LID2 of FIG. 9Balternately. However, when a reduction in detection accuracy etc. isacceptable to some extent, it is also possible to obtain the direction,the position, etc. in which the object is located by forming only one ofthe irradiation light intensity distribution LID1 of FIG. 9A and theirradiation light intensity distribution LID2 of FIG. 9B.

6. Specific Configuration of Optical Detecting Device

Next, a specific configuration example of the optical detecting devicewill be described by using FIG. 11.

In a configuration example of FIG. 11, the light source section LS1 isprovided at one end of the light guide LG as indicated by F1 of FIG. 11.Moreover, the second light source section LS2 is provided at the otherend of the light guide LG as indicated by F2. As a result of the lightsource section LS1 emitting a source light toward the light entranceface at one end (F1) of the light guide LG, the first irradiation lightintensity distribution LID1 is formed (set) in an object detectionregion. On the other hand, as a result of the light source section LS2emitting a second source light toward the light entrance face at theother end (F2) of the light guide LG, the second irradiation lightintensity distribution LID2 having an intensity distribution which isdifferent from that of the first irradiation intensity distribution LID1is formed in the detection region.

That is, in the configuration example of FIG. 11, the light sourcesections LS1 and LS2 are provided at the ends of the light guide LG, andthe light source sections LS1 and LS2 are turned on alternately inopposite phase as shown in FIG. 12A which will be described later,whereby a state shown in FIG. 9A and a state shown in FIG. 9B arecreated alternately. In other words, the reflected light from the objectis received by alternately forming the irradiation intensitydistribution LID1 in which the intensity at one end of the light guideLG is high and the irradiation intensity distribution LID2 in which theintensity at the other end of the light guide LG is high, and thedirection etc. in which the object is located is determined based on theresult of the light thus received.

According to this configuration example, it is necessary simply toprovide only one light guide LG. As a result, it is possible to make theoptical detecting device compact, for example.

Incidentally, in FIG. 11, only one light guide LG is provided; however,in addition to the light guide LG, a second light guide may be provided.In this case, the light guide LG and the second light guide may bearranged side by side in a direction intersecting (orthogonal to) aplane along the direction in which the light guide LG and theirradiation direction setting section LE are arranged.

Moreover, the light source section LS1 of FIG. 11 is provided at one endof the light guide LG, and the light source section LS2 is provided atthe other end of the second light guide.

As a result of the light source section LS1 emitting a source lighttoward the light entrance face at one end of the light guide LG1, thefirst irradiation light intensity distribution LID1 is formed in anobject detection region. On the other hand, as a result of the lightsource section LS2 emitting a second source light toward the lightentrance face at the other end of the second light guide, the secondirradiation light intensity distribution LID2 having an intensitydistribution which is different from that of the first irradiationintensity distribution LID1 is formed in the detection region. Thisconfiguration example has an advantage that the optical design foradjusting the light exit characteristics of the light guide can besimplified.

That is, as in the configuration example of FIG. 11, in the techniqueusing one light guide LG, it is difficult to adjust the light exitcharacteristics by silk printing processing or the like. In other words,when the light exit characteristics are adjusted by processing thesurface of the light guide LG such that the intensity of the irradiationlight intensity distribution LID1 changes linearly, the intensity of theirradiation light intensity distribution LID2 does not change linearly.On the other hand, when the light exit characteristics are adjusted byprocessing the surface of the light guide LG such that the intensity ofthe irradiation light intensity distribution LID2 changes linearly, theintensity of the irradiation light intensity distribution LID1 does notchange linearly. From this standpoint, the configuration in which twolight guides are provided has the advantage that such an optical designcan be simplified.

Incidentally, even if the characteristics of an intensity change become,for example, hyperbolic characteristics, not linear characteristics asshown in FIG. 10A, it is possible to deal with such situations bycorrection processing using software or the like. That is, even if thecharacteristics do not optically become linear characteristics, it ispossible to make an adjustment such that the characteristics becomelinear characteristics by performing correction processing on the resultof the received light. Therefore, when such correction processing isperformed, by adopting a configuration in which only one light guide LGis provided as shown in FIG. 11 instead of providing two light guides,it is possible to make the optical detecting device compact, forexample.

According to the above-described optical detecting device of thisembodiment, by using a concentric curved light guide, it is possible toperform angle sensing. In addition, since the light guide has a curvedshape, it is possible to make an irradiation light exit radially. As aresult, it is possible to detect the direction, the position, etc. inwhich the object is located in a wider range as compared to a techniqueusing a linear light guide or the like. For example, in the techniqueusing a linear light guide, it is necessary to lengthen the light guideto make it possible to perform detection in a wide range. Thisundesirably makes the system large-scale. On the other hand, accordingto this embodiment, as shown in FIG. 8, by just placing asmall-footprint irradiating section, the direction, the position, etc.in which the object is located can be detected in a wide range.

In particular, when the optical detecting device is attached to theattaching device as shown in FIG. 1, the optical detecting device isrequired to have a small footprint and an ability to perform detectionin a wide range. The optical detecting device described in FIGS. 8 to 11is a detecting device most suitable for being attached to the attachingdevice as an option.

7. Position Detection Technique

Next, an example of a technique of detecting the position of an objectby using the optical detecting device of this embodiment will bedescribed. FIG. 12A shows an example of a signal waveform aboutlight-emitting control of the light source sections LS1 and LS2. Asignal SLS1 is a light-emitting control signal for the light sourcesection LS1, and a signal SLS2 is a light-emitting control signal forthe light source section LS2. These signals SLS1 and SLS2 are oppositephase signals. Moreover, a signal SRC is a received-light signal.

For example, the light source section LS1 is turned on (emits light)when the signal SLS1 is at H level, and is turned off when the signalSLS1 is at L level. Moreover, the light source section LS2 is turned on(emits light) when the signal SLS2 is at H level, and is turned off whenthe signal SLS2 is at L level. Therefore, in a first period T1 of FIG.12A, the light source section LS1 and the light source section LS2 areturned on alternately. That is, in a period in which the light sourcesection LS1 is turned on, the light source section LS2 is turned off. Asa result, the irradiation light intensity distribution LID1 shown inFIG. 9A is formed. On the other hand, in a period in which the lightsource section LS2 is turned on, the light source section LS1 is turnedoff. As a result, the irradiation light intensity distribution LID2shown in FIG. 9B is formed.

As described above, the control section 60 of FIG. 8 performs control soas to make (turn on) the light source section LS1 and the light sourcesection LS2 emit light in the first period T1. In addition, in the firstperiod T1, the direction in which the object is located as seen from theoptical detecting device (the irradiating section) is detected.Specifically, for example, light-emitting control is performed in thefirst period T1 such that Ga/Gb=1 and the sum of the controlledvariables Ia and Ib becomes constant as in equations (6) and (7)described above. Then, the direction DDB in which the object OB islocated as shown in FIG. 10B is obtained. For example, the ratio betweenthe attenuation coefficients fa/fb is obtained by equations (10) and(11) above, and the direction DDB in which the object OB is located isobtained by the technique described in FIGS. 10A and 10B.

Then, in a second period T2 after the first period T1, the distance tothe object OB (the distance in a direction along the direction DDB) isdetected based on the result of the light received by the lightreceiving section RU. Based on the detected distance and the directionDDB in which the object OB is located, the position of the object isdetected. That is, by obtaining the distance from the placement positionPE in which the optical detecting device is placed to the object OB andthe direction DDB in which the object OB is located in FIG. 10B, it ispossible to determine the X and Y coordinate positions of the object OBin the X-Y plane of FIG. 8. As described above, by obtaining thedistance based on the time lag between the time at which the lightsource is turned on and the time at which the light is received andcombining the distance thus obtained with the angle result, it ispossible to determine the position of the object OB.

Specifically, in FIG. 12A, time Δt between the time at which the lightsource sections LS1 and LS2 are made to emit light by the light emissioncontrol signals SLS1 and SLS2 and the time at which the received-lightsignal SRC becomes active (the time at which the reflected light isreceived) is detected. That is, time Δt from when the lights from thelight source sections LS1 and LS2 are reflected from the object OB tillwhen the reflected lights are received by the light receiving section RUis detected. By detecting the time Δt, it is possible to detect thedistance to the object OB because the velocity of light is known. Thatis, the distance is obtained based on the velocity of light by measuringthe time lag (the time) between the times at which the lights havearrived.

Incidentally, since the velocity of time is considerably fast, it isdifficult to detect the time Δt by obtaining a simple difference byusing only an electrical signal. To solve such a problem, it ispreferable to modulate the light-emitting control signal as shown inFIG. 12B. Here, FIG. 12B shows a schematic signal waveform exampleschematically showing the intensity of light (the amount of current) bythe amplitudes of the control signals SLS1 and SLS2.

Specifically, in FIG. 12B, the distance is detected by well-knowncontinuous-wave modulation TOF (time of flight), for example. In thecontinuous-wave modulation TOF, a continuous light which has beenintensity-modulated by continuous waves with constant periodicity isused. Then, the waveform of the reflected light is demodulated byirradiating the intensity-modulated light and receiving the reflectedlight multiple times at time intervals, each time interval being shorterthan the modulation period, and the distance is detected by obtainingthe phase difference between the irradiation light and the reflectedlight. Incidentally, in FIG. 12B, intensity modulation may be performedon the light corresponding to any one of the control signals SLS1 andSLS2. Moreover, instead of a clock waveform shown in FIG. 12B, awaveform modulated by continuous triangular waves or sine waves may beused. Furthermore, the distance may be detected by pulse modulation TOFusing a pulse light as a light subjected to continuous modulation. Thedetails of the distance detection technique are disclosed inJP-A-2009-8537, for example.

In FIG. 13, a modified example of the optical detecting device is shown.In FIG. 13, first and second irradiating sections EU1 and EU2 areprovided. The first and second irradiating sections EU1 and EU2 areplaced a given distance DS away from each other in a direction along theplane of the detection region RDET in which the object OB is detected.That is, the first and second irradiating sections EU1 and EU2 areplaced a distance DS away from each other along the X-axis direction ofFIG. 8.

The first irradiating section EU1 radially emits first irradiationlights with different intensities in accordance with the irradiationdirection. The second irradiating section EU2 radially emits secondirradiation lights with different intensities in accordance with theirradiation direction. The light receiving section RU receives a firstreflected light generated as a result of the first irradiation lightfrom the first irradiating section EU1 being reflected from the objectOB and a second reflected light generated as a result of the secondirradiation light from the second irradiating section EU2 beingreflected from the object OB. Then, the detecting section 50 detects theposition POB of the object OB based on the result of the light receivedby the light receiving section RU.

Specifically, the detecting section 50 detects the direction in whichthe object OB is located with respect to the first irradiating sectionEU1 as a first direction DDB1 (an angle θ1) based on the result of thereceived light, i.e., the first reflected light. Moreover, the detectingsection 50 detects the direction in which the object OB is located withrespect to the second irradiating section EU2 as a second direction DDB2(an angle θ2) based on the result of the received light, i.e., thesecond reflected light. Then, the detecting section 50 obtains theposition POB of the object OB based on the detected first direction DDB1(θ1) and second direction DDB2 (θ2) and the distance DS between thefirst and second irradiating sections EU1 and EU2.

According to the modified example of FIG. 13, it is possible to detectthe position POB of the object OB without obtaining the distance betweenthe optical detecting device and the object OB as in FIGS. 12A and 12B.

8. Regulation of Irradiation Direction

Now, when an object such as a finger of the user is detected by settinga detection region, erroneous detection may be performed if theirradiation light from the irradiating section EU becomes a light spreadin the Z direction of FIG. 8. That is, there is a possibility that thebody of the user, not a finger of the user which is an object to bedetected, is detected. For example, in FIG. 8, there is a possibilitythat, when the body of the user just approaches the screen 20, it isdetected erroneously that a finger of the user which is an object to bedetected is present in the detection region RDET.

It is for this reason that, in the optical detecting device of thisembodiment, an irradiation direction regulating section (an irradiationdirection restricting section) which regulates the irradiation directionof the irradiation light such that the irradiation light travels in adirection (a direction parallel to the projection surface) along theplane of the object detection region RDET (the plane parallel to the X-Yplane) is provided. Specifically, in FIG. 14A, the irradiation directionregulating section is implemented in the form of a slit SL. The slit SLhas a first slit surface SFL1 and a second slit surface SFL2 along theplane of the detection region RDET. As described above, in thisembodiment, the irradiation direction regulating section of the opticaldetecting device is implemented by providing the slit SL having anopening in the irradiation direction in a housing HS of the opticaldetecting device.

By providing such a slit SL, the light from the light guide LG isregulated so as to travel in the direction along the slit surfaces SFL1and SFL2. In this way, it is possible to regulate the irradiation lightemitted from the irradiating section EU of FIG. 8 so as to become alight parallel to the X-Y plane. This makes it possible to prevent theirradiation light toward the detection region from spreading in the Zdirection and prevent the body of the user from being erroneouslydetected as an object such as a finger or a touch pen when the body ofthe user approaches the screen 20. As a result, it is possible torealize appropriate object position detection without providing a devicefor detecting the position in the Z direction.

Moreover, in FIG. 14B, a depressed section is formed in the slitsurfaces SFL1 and SFL2. That is, in FIG. 14A, the slit surfaces SFL1 andSFL2 are flat; in FIG. 14B, the slit surfaces SFL1 and SFL2 are notflat, but depressed. By providing such a depressed section, it ispossible to prevent surface reflection on the slit surfaces SFL1 andSFL2 and make the irradiation light which is more parallel to the X-Yplane travel toward the detection region RDET.

Incidentally, it is also possible to realize the same function as thedepressed section by, for example, applying nonreflective coating to thesurfaces of the slit surfaces SFL1 and SFL2. Moreover, FIGS. 14A and 14Bshow a case in which the irradiation direction regulating sectionregulating deflection of the irradiation light in the Z direction isimplemented in the form of the slit SL. However, the irradiationdirection regulating section may be implemented by, for example, usingan optical sheet such as a louver film. For example, the louver film LFof FIG. 9A has the function of regulating the direction in which thelight exiting from the light guide LG travels so that the directioncoincides with a normal direction. Therefore, in order to realize thesame function as the function of the irradiation direction regulatingsection implemented in the form of the slit SL, it is necessary simplyto provide a louver film placed so as to regulate the direction in whichthe light from the light guide LG travels so that the directioncoincides with the direction parallel to the X-Y plane of FIG. 8.

Incidentally, the descriptions heretofore deal with the configuration ofthe optical detecting device having a curved light guide. However, theoptical detecting device of this embodiment is not limited to such aconfiguration, and various modifications are possible. For example, theoptical detecting device may be an optical detecting device using alinear light guide.

9. Detailed Structural Example of Attaching Device

Next, a detailed structural example of the attaching device of thisembodiment will be described by using FIG. 15 and FIGS. 16A and 16B.

FIG. 15 is a side view of the attaching device of this embodiment, asviewed from the side thereof (from the X direction). The attachingsection 31 for attaching the attaching device to the ceiling isconnected and secured to the attaching section 32 by attaching fittings(screws, nuts, and the like) 100 of the attaching section 32. The imageprojection device 10 is connected and secured to the attaching device byattaching fittings 102 and 104 of the attaching section 32.

In FIG. 15, the attaching section 32 and the attaching section 33 areintegrally formed by the base fittings. The optical detecting device 40(the irradiating section EU) is connected and secured to the attachingdevice by attaching fittings 106 of the attaching section 33.Incidentally, the light receiving section RU of the optical detectingdevice 40 is provided between the image projection device 10 and theirradiating section EU, for example.

FIG. 16A is a front view of the attaching device of this embodiment, asviewed from the front (from the projection surface side). As shown inFIG. 16A, the attaching device is connected and secured to the ceiling400 by the attaching section 31. Moreover, the optical detecting device40 is secured to the attaching device by the attaching section 33 insuch a way as to be placed between the image projection device 10 andthe projection surface 22 (the wall on which the projection surface isprovided).

Incidentally, FIG. 15 shows a case in which the attaching section 32 andthe attaching section 33 are integrally formed by the base fittings.However, this embodiment is not limited thereto. For example, as shownin FIG. 16B, a joining section 34 (a joint) for joining the fittings ofthe attaching section 32 and the fittings of the attaching section 33together may be provided. The joining section 34 is formed of attachingfittings 112 and 114 such as screws, nuts, and connecting base fittings.

With the configuration shown in FIG. 16B, it is possible to connect theattaching section 32 and the attaching section 33 detachably by thejoining section 34. Therefore, it is possible to provide the attachingdevice as normal ceiling-hung fittings of the image projection device 10to the user who does not require the optical detecting device 40 bydetaching the attaching section 33, for example. On the other hand, itis possible to provide the attaching device as ceiling-hung fittingswith the optical detecting device to the user who requires the opticaldetecting device 40 by connecting the attaching section 33 by using thejoining section 34.

10. Calibration

Now, in the optical detecting device 40, it is preferable to performcalibration for position detection in order to realize appropriateobject position detection. It is for this reason that an I/F (interface)section 42 performing interface processing between the optical detectingdevice 40 and the image projection device 10 and the like is provided inthe optical detecting device 40 in FIG. 17. The optical detecting device40 transmits information for calibration to the image projection device10 via the I/F section 42, or, in a normal detection period, transmitsthe detected position information to the image projection device 10 viathe I/F section 42.

As shown in FIG. 17, the image projection device 10 includes an I/Fsection 16 and a communication section 18. The image projection device10 receives the information for calibration from the optical detectingdevice 40 via the I/F section 16. Moreover, in a normal positiondetection period, the image projection device 10 receives the detectedposition information from the optical detecting device 40 via the I/Fsection 16. The image projection device 10 transmits the receivedinformation for calibration or the detected position information in thenormal detection period to a PC (a personal computer) which is aninformation processor via the communication section 18. Thecommunication section 18 may perform wired communication or may performwireless communication such as a wireless LAN. Incidentally, theinformation for calibration is, for example, a program product forcalibration or detected position information in a calibration period.

The I/F section 42 can be implemented by using USB (universal serialbus), for example. In this case, as shown in FIG. 17, the I/F section 42(the USB interface) of the optical detecting device 40 is connected tothe I/F section 16 of the image projection device 10 via a USB cable. Byusing such USB, it is possible to connect the optical detecting device40 by using a USB terminal which is inherently provided in the imageprojection device 10, and thereby provide greater versatility.

Moreover, the use of USB allows the optical detecting device 40 toreceive a power supply from the image projection device 10 via the I/Fsection 42. Specifically, the optical detecting device 40 receives apower supply from the image projection device 10 via a VBUS of USB. Theoptical detecting device 40 operates based on the received power supply.For example, the optical detecting device 40 makes the light emittingelement emit light by using the received power supply or operates theICs (integrated circuit devices) of the detecting section 50, thecontrol section 60, and the like.

Incidentally, the I/F section 42 of the optical detecting device 40 isnot limited to a USB interface, and a wired fast-speed serial interfaceother than USB may be used. In this case, it is preferable that the I/Fsection 42 be a fast-speed serial interface which can supply or receivea power supply. Alternatively, the I/F section 42 may be a wirelessinterface such as Bluetooth or a wireless LAN, not a wired interface. Inaddition, the optical detecting device 40 and the PC (in a broad sense,the information processor) of FIG. 17 may be so configured as to performcommunication by using a wireless interface. In this case, theinformation for calibration or the detected position information in thenormal detection period is transmitted to the PC via the wirelessinterface.

In this embodiment, after the image projection device 10 projects animage of a screen for calibration shown in FIG. 19C, which will bedescribed later, on the projection surface 22, the detecting section 50of FIG. 8 detects the position information of the object in thedetection region. Then, the optical detecting device 40 transmits thedetected position information of the object (in a broad sense, theinformation for calibration) to the image projection device 10.Specifically, the optical detecting device 40 transmits the detectedposition information to the image projection device 10 via the I/Fsection 42.

The image projection device 10 then transmits, via the communicationsection 18, the received position information to the PC which controlsthe image projection device 10. This allows the PC (the program productoperating on the PC) to determine, for example, whether or not the userindicates a correct position on the screen for calibration.

Moreover, the optical detecting device 40 stores a program product forcalibration, the program product for performing calibration processing,in a storing section (nonvolatile memory such as EEPROM) thereof. Theoptical detecting device 40 transmits the program product forcalibration to the image projection device 10 via the I/F section 42.

Then, the image projection device 10 transmits the received programproduct for calibration to the PC via the communication section 18. Thisallows the PC to install the received program product for calibrationand perform calibration processing by the program product forcalibration. Incidentally, the detected position information or theprogram product for calibration may be transmitted directly to the PCvia the wireless I/F section 42.

Next, a specific example of the calibration processing of thisembodiment will be described by using a flowchart of FIG. 18.

At the time of installation of the image projection device 10, the userattaches the image projection device 10 to the attaching device of thisembodiment by using the attaching section 32. Moreover, the userattaches the optical detecting device 40 to the attaching device byusing the attaching section 33. The user then connects the imageprojection device 10 and the optical detecting device 40 by using a USBcable, for example. Then, the image projection device 10 supplies apower supply to the optical detecting device 40 via USB (step S1),whereby the optical detecting device 40 starts operating.

Next, the optical detecting device 40 transmits a program product forcalibration to the image projection device 10 via USB (step S2). Then,the image projection device 10 transmits the program product forcalibration to the PC via a wireless LAN or wired communication (stepS3).

Next, as shown in FIG. 19A, installation of the program product forcalibration is started in the PC (step S4). When the installation isfinished, a calibration start selection screen shown in FIG. 19B isdisplayed on the display section of the PC (step S5).

When the user selects start of calibration on the calibration startselection screen of FIG. 19B (step S6), the image projection device 10projects an image of a screen for calibration shown in FIG. 19C on thescreen 20 (the projection surface) according to an instruction from thePC (step S7). On the screen for calibration of FIG. 19C, a plurality ofpoints to be indicated (pointed) by the user are displayed. In addition,a cursor for notifying the user of a point to be indicated by the useris also displayed. Therefore, as shown in FIG. 1, the user indicates apoint at which the cursor is located by using a finger or the like.Then, the optical detecting device 40 detects a position on the screenfor calibration, the position indicated by the user by using a finger orthe like (step S8). That is, the optical detecting device 40 detects theX and Y coordinates of the position of the finger of the user.

The optical detecting device 40 transmits the detected positioninformation to the image projection device 10 via USB (step S9). Then,the image projection device 10 transmits the detected positioninformation to the PC via a wireless LAN or wired communication (stepS10).

Next, the PC determines a position indicated by the user and performscalibration processing (step S11). For example, the PC compares theposition of each point of FIG. 19C with the position actually indicatedby the user, and performs the calibration processing for adjusting thedisplacement of the detected position. Then, the PC determines whetheror not the calibration is completed (step S12), and repeats theprocessing in steps S8 to S11 until all the calibration operations arecompleted.

The calibration adjustment information (the information for adjustingthe displacement of the detected position) obtained by the calibrationprocessing described above is stored in the PC, for example. In a normaloperation state in which the optical detecting device 40 performs normalposition detection, processing for correcting the displacement of thedetected position is performed based on the calibration adjustmentinformation. Incidentally, processing for correcting the displacement ofthe detected position may be performed in the optical detecting device40 by transmitting the calibration adjustment information from the PC tothe optical detecting device 40 via the image projection device 10.

By doing so, it is possible to obtain the calibration adjustmentinformation by performing the calibration processing at the time ofinstallation of the image projection device 10. In a normal operationstate after installation of the image projection device 10, it ispossible to realize precise position detection by performing processingfor correcting the displacement of the detected position by using theobtained calibration adjustment information.

While the embodiment has been described in detail, it will be apparentto those skilled in the art that many modifications are possible unlessthey substantively depart from the scope of the subject matter and theeffect of the invention. Therefore, such modifications should beconstrued as being included in the scope of the invention. For example,a term which has been described along with a more comprehensive term ora synonymous term at least onetime in the specification or drawings canbe replaced with the more comprehensive term or the synonymous term inany location in the specification or drawings. Moreover, it is to beunderstood that the configurations and operations of the attachingdevice, the optical detecting device, the projection display device,etc. are not limited to those described in the above embodiment, and maybe modified in numerous ways.

The entire disclosure of Japanese Patent Application No. 2010-120205,filed May 26, 2010 is expressly incorporated by reference herein.

What is claimed is:
 1. A projection display system comprising: an imageprojection device projecting an image on a projection surface; anoptical detecting device that detects position information of an objectlocated in a detection region which is set along the projection surface;and an attaching device, wherein the optical detecting device includesan irradiating section emitting an irradiation light toward thedetection region, a light receiving section receiving a reflected lightgenerated as a result of the irradiation light being reflected from theobject, and a detecting section detecting the position information ofthe object based on the result of the light received by the lightreceiving section, and the attaching device includes a first attachingsection that is in a bar shape elongating in a first direction, and oneend of the first attaching section is attached to a support supportingthe attaching device, a second attaching section that is in a plateshape elongating in a second direction perpendicular to the firstdirection, a first area in one end on a top surface of the secondattaching section is connected to the other end of the first attachingsection, a second area, which is opposite to the first area, in the oneend on a bottom surface of the second attaching section is attached tothe image projection device, and a third attaching section that iscontinuously provided at the other end of the second attaching sectionin the second direction, a third area of a bottom surface of the thirdattaching section is attached to the optical detecting device so thatthe optical detecting device is spaced apart from the image projectiondevice in the second direction.
 2. The projection display systemaccording to claim 1, wherein the irradiating section emits theirradiation light with different intensities in accordance with adirection in which the irradiation light is emitted.
 3. The projectiondisplay system according to claim 1, wherein the irradiating sectionincludes a light source section emitting a source light, a light guidewhich is curved and which guides the source light from the light sourcesection, and an irradiation direction setting section receiving thesource light exiting from an outer circumferential side of the lightguide and setting an irradiation direction of the irradiation light suchthat the irradiation light travels from an inner circumferential side tothe outer circumferential side of the light guide.
 4. The projectiondisplay system according to claim 1, wherein the optical detectingdevice has a first irradiating section and a second irradiating section,the first irradiating section radially emits first irradiation lightwith different intensities in accordance with a direction in which thefirst irradiation light is emitted, the second irradiating sectionradially emits second irradiation light with different intensities inaccordance with a direction in which the second irradiation light isemitted, the light receiving section receives a first reflected lightgenerated as a result of the first irradiation light being reflectedfrom the object and a second reflected light generated as a result ofthe second irradiation light being reflected from the object, and thedetecting section detects a position of the object based on the resultof the first and second reflected lights received by the light receivingsection.
 5. The projection display system according to claim 1, whereinthe detecting section detects the position information of the object inthe detection region after the image projection device projects an imagefor calibration on the projection surface, and the optical detectingdevice transmits the detected position information of the object to theimage projection device or an information processor controlling theimage projection device.
 6. The projection display system according toclaim 5, wherein the optical detecting device includes an interfacesection, and the optical detecting device transmits information forcalibration via the interface section.
 7. The projection display systemaccording to claim 6, wherein the optical detecting device receiveselectric power from the image projection device via the interfacesection.